U.S. Pat. No. 5,310,808 to R. A. Grey describes various vinyl phosphonate derivatives which are useful in the manufacture of flame retarded thermoplastic copolymers. Various aryl group-containing vinylphosphonate species are embraced by a formula depicted at col. 3, lines 14-26 of this patent in which a linear or branched divalent hydrocarbyl radical, B, is depicted as being bonded at either end thereof to the two oxygen atoms of the moiety 
with the structures xe2x80x94CH2xe2x80x94CH2xe2x80x94 and xe2x80x94CH(CH3) xe2x80x94CH2xe2x80x94 being given as examples of preferred groups for B.
The present invention are certain novel neopentylene phosphonate compounds containing, as the type of divalent group B shown in both the compounds of U.S. Pat. No. 5,310,808 and intermediates thereof, the novel divalent linkage xe2x80x94CH2xe2x80x94C(CH3)2xe2x80x94CH2xe2x80x94.
The compounds of the present invention are, for example, embraced by the formula 
where: Ar is substituted or unsubstituted phenyl;
A is selected from the group consisting of hydrogen and, if conjoint with B, CH2; and
B is selected from the group consisting of hydroxy, oxyacyl, and, if conjoint with A, CH2. It will be appreciated that having A and B conjoint as CH2 makes the entire grouping C less than A(B) a vinyl group.
A particularly preferred embodiment of the present invention relates to final compounds where the group C less than A(B) does form a vinyl structure having A and B being conjoint as the moiety CH2. This type of compound class is exemplified by the compound neopentylene 1-phenylvinylphosphonate which has the formula: 
Another embodiment of the present invention is exemplified by the class of novel intermediates for the previously described vinyl group-containing compound. One specific compound of this type is neopentylene 1-acetoxy-1-phenylethylphosphonate which is of the formula: 
Yet another embodiment of the present invention is the novel intermediate compounds for the previously described 1-acetoxy containing compounds. These compounds are exemplified by the compound neopentylene 1-hydroxy-1-phenylethylphosphonate which is of the formula: 
The process for forming the desired final products of the type exemplified by (I) involves the reaction of neopentylene hydrogen phosphonate with acetophenone to yield compounds as exemplified by (III) followed by acetylation with acetic anhydride to form the type of compound exemplified by (II) followed by acid-catalyzed deacetylation of (II) to form the final desired compound (I).